1. Field of the Invention
The present invention relates to a wireless communication apparatus, and more particularly, to a wireless communication apparatus capable of performing a mutual communication according to a sniff parameter calculated based on the information with respect to sniff slave apparatuses connected with a master apparatus in a sniff mode for performing a communication for a determined time between the master apparatus and the slave apparatuses. The present application is based on Korean Application No. 2001-53176, filed Aug. 31, 2001, which is incorporated herein by reference.
2. Description of the Related Art
Bluetooth is a communication technology capable of transmitting wirelessly information such as letter data, sound data, and video data at a distance of 10 to 100 m.
A Bluetooth apparatus, which can mutually communicate according to the Bluetooth communication method, sets up a connection status that communicates through operations such as an inquiry, an inquiry scan, a page, and a page scan. From this process, a master apparatus and a slave apparatus are determined according to their respective roles.
When a new connection status is set up between the Bluetooth apparatuses, an operation clock and a frequency pattern should be adjusted between the Bluetooth apparatuses. In the process for setting up the connection status, the inquiry is an operation of repeatedly sending an operation frequency from the master apparatus so that the slave apparatus can adjust the frequency pattern with the master apparatus. The inquiry scan is a process performed in the slave apparatus. The inquiry scan detects a transmitted frequency, and adjusts a synchronism with the detected frequency. The page is a process for sending a clock signal from the master apparatus so that the slave apparatus can adjust for the operation clock of the master apparatus. The page scan is used to detect the transmitted clock signal and to adjust the synchronism thereby. The page scan is done by the slave apparatus. A network, which is formed by two or more slave apparatuses setting up the connection status in regard to the master apparatus, is a Piconet.
According to the Bluetooth communication method currently in use, a master apparatus can communicate with seven slave apparatuses by connecting the slave apparatuses to achieve an active status in the Piconet. Moreover, to connect a new slave apparatus to the Piconet, the master apparatus terminates the active status with respect to one slave apparatus among the seven slave apparatuses, and performs a communication connection in the active status with the new slave apparatus.
On the other hand, in the Bluetooth communication method, the master apparatus and the slave apparatuses are operated in an active mode for performing a normal communication with the slave apparatuses, and in a hold mode, a sniff mode, and a park mode which enables the communication apparatus to conserve power. The hold mode is a typical mode used when there is no need to send data for a relatively long period. The sniff mode is a mode for transmitting data from a certain time mutually set up between the master apparatus and the slave apparatuses for a predetermined time. The park mode is a mode for performing mutual communication between the master apparatus and the slave apparatus intermittently to allow the slave apparatus to synchronize with the master apparatus, and to acquire conversion to the active mode.
The slave apparatuses, which operate in one of the hold mode, the sniff mode, and the park mode, communicate with the master apparatus for a predetermined time during the operation time of the slave apparatuses operated in the active mode. A data transmission period (hereinbelow, referred to as a ‘sniff period’) of the master apparatus and the slave apparatuses according to the sniff mode is repeatedly generated at a predetermined cycle until the slave apparatuses operated in the sniff mode are converted to the active mode.
At this time, each of the slave apparatuses operated in the sniff mode can have a start time, an allocated time of the sniff period, and a sniff period generation cycle (hereinbelow, referred to as a ‘sniff parameter’), respectively different. The sniff parameter is determined through a link management protocol (LMP) among Bluetooth protocol level structures. The master apparatus of the Piconet including the slave apparatuses (hereinbelow, referred to as ‘a sniff slave apparatus’) operated in the sniff mode allocates the different sniff parameters to the sniff slave apparatuses, and stores the differently allocated sniff parameters.
Accordingly, the master apparatus scheduling the data communication with each of the slave apparatuses needs a memory packet for storing the sniff parameter allocated to the slave apparatuses operated in the sniff mode. Therefore, a number of memory packets should be provided corresponding to at least the number of the slave apparatuses operated in the sniff mode. For example, when seven sniff slave apparatuses are connected with one Piconet, seven memory packets for storing the sniff parameter allocated to the seven sniff slave apparatuses are needed. In addition, seven sniff time sheets (hereinbelow, referred to as a ‘sniff timer’) for notifying the end of the corresponding sniff period to a controller (not shown) of the master apparatus by checking the timer with respect to the sniff period of each of the sniff slave apparatuses are disposed at the master apparatus in the conventional sniff mode.
In the meantime, it will sometimes happen when communicating between the master apparatus and the slave apparatuses through the conventional sniff mode that the sniff period is not allocated to the corresponding sniff slave apparatuses due to a cyclic operation having a higher priority level than the sniff slave apparatuses. The inquiry, the inquiry scan, the page, and the page scan, which are performed by the master apparatus and the slave apparatuses in the Piconet, are such cyclic operations. A supervision timeout rule, which stops the operation needed for the communication connection when a predetermined time set up for communication connection has passed, is applied in the Bluetooth communication method. Accordingly, when the operation, which is needed for the communication connection during the sniff period allocated between the master apparatus and the slave apparatuses, is not supported, the communication connection between the master apparatus and the slave apparatuses fails.
As an example of the communication apparatus utilizing the Bluetooth communication method is a personal portable terminal. Thus, memory packets corresponding to the number of the personal portable terminals operated in the sniff mode should be provided in each of the personal portable terminals. But it is not desirable to provide such memory packets, because this makes it difficult to reduce the size of the product and causes an increase in production costs. Moreover, since the master apparatus consecutively performs the data communication through the sniff parameters stored in each of the memory packets, the scheduling time for the data communication is increased.
The scheduling time for the data communication of the master apparatus is increased, since the master apparatus should allocate the sniff period in regard to each of the sniff slave apparatuses after finding the period not having a cyclic active operation when there is the cyclic active operation performed by the Piconet master apparatus.